NAME
DataFlow - A framework for dataflow processing
VERSION
version 1.121260
SYNOPSIS
use DataFlow;
my $flow = DataFlow->new(
procs => [
DataFlow::Proc->new( p => sub { do this thing } ), # a Proc
sub { ... do something }, # a code ref
'UC', # named Proc
[ # named Proc, with parameters
CSV => {
direction => 'CONVERT_TO',
text_csv_opts => { binary => 1 },
}
],
# named Proc, named "Proc"
[ Proc => { p => sub { do this other thing }, deref => 1 } ],
DataFlow->new( ... ), # another flow
]
);
$flow->input( );
my $output = $flow->output();
my $output = $flow->output( );
# other ways to invoke the constructor
my $flow = DataFlow->new( sub { .. do something } ); # pass a sub
my $flow = DataFlow->new( [ # pass an array
sub { ... do this },
'UC',
[
HTMLFilter => (
search_xpath => '//td',
result_type => 'VALUE'
)
]
] );
my $flow = DataFlow->new( $another_flow ); # pass another DataFlow or Proc
# other way to pass the data through
my $output = $flow->process( qw/long list of data/ );
DESCRIPTION
A "DataFlow" object is able to accept data, feed it into an array of
processors (DataFlow::Proc objects), and return the result(s) back to
the caller.
ATTRIBUTES
name
(Str) A descriptive name for the dataflow. (OPTIONAL)
default_channel
(Str) The name of the default communication channel. (DEFAULT:
'default')
auto_process
(Bool) If there is data available in the output queue, and one calls the
"output()" method, this attribute will flag whether the dataflow should
attempt to automatically process queued data. (DEFAULT: true)
procs
(ArrayRef[DataFlow::Role::Processor]) The list of processors that make
this DataFlow. Optionally, you may pass CodeRefs that will be
automatically converted to DataFlow::Proc objects. (REQUIRED)
The "procs" parameter will accept some variations in its value. Any
"ArrayRef" passed will be parsed, and additionaly to plain
"DataFlow::Proc" objects, it will accept: "DataFlow" objects (so one can
nest flows), code references ("sub{}" blocks), array references and
plain text strings. Refer to DataFlow::Types for more information on
these different forms of passing the "procs" parameter.
Additionally, one may pass any of these forms as a single argument to
the constructor "new", plus a single "DataFlow", or "DataFlow:Proc" or
string.
METHODS
has_queued_data
Returns true if the dataflow contains any queued data within.
clone
Returns another instance of a "DataFlow" using the same array of
processors.
input
Accepts input data for the data flow. It will gladly accept anything
passed as parameters. However, it must be noticed that it will not be
able to make a distinction between arrays and hashes. Both forms below
will render the exact same results:
$flow->input( qw/all the simple things/ );
$flow->input( all => 'the', simple => 'things' );
If you do want to handle arrays and hashes differently, we strongly
suggest that you use references:
$flow->input( [ qw/all the simple things/ ] );
$flow->input( { all => the, simple => 'things' } );
Processors using the DataFlow::Policy::ProcessInto policy (default) will
process the items inside an array reference, and the values (not the
keys) inside a hash reference.
channel_input
Accepts input data into a specific channel for the data flow:
$flow->channel_input( 'mydatachannel', qw/all the simple things/ );
process_input
Processes items in the array of queues and place at least one item in
the output (last) queue. One will typically call this to flush out some
unwanted data and/or if "auto_process" has been disabled.
output_items
Fetches items, more specifically objects of the type DataFlow::Item,
from the data flow. If called in scalar context it will return one
processed item from the flow. If called in list context it will return
all the items from the last queue.
output
Fetches data from the data flow. It accepts a parameter that points from
which data channel the data must be fetched. If no channel is specified,
it will default to the 'default' channel. If called in scalar context it
will return one processed item from the flow. If called in list context
it will return all the elements in the last queue.
reset
Clears all data in the dataflow and makes it ready for a new run.
flush
Flushes all the data through the dataflow, and returns the complete
result set.
process
Immediately processes a bunch of data, without touching the object
queues. It will process all the provided data and return the complete
result set for it.
proc_by_index
Expects an index (Num) as parameter. Returns the index-th processor in
this data flow, or "undef" otherwise.
proc_by_name
Expects a name (Str) as parameter. Returns the first processor in this
data flow, for which the "name" attribute has the same value of the
"name" parameter, or "undef" otherwise.
FUNCTIONS
dataflow
Syntax sugar function that can be used to instantiate a new flow. It can
be used like this:
my $flow = dataflow
[ 'Proc' => p => sub { ... } ],
...
[ 'CSV' => direction => 'CONVERT_TO' ];
$flow->process('bananas');
HISTORY
This is a framework for data flow processing. It started as a spin-off
project from the OpenData-BR initiative.
As of now (Mar, 2011) it is still a 'work in progress', and there is a
lot of progress to make. It is highly recommended that you read the
tests, and the documentation of DataFlow::Proc, to start with.
An article has been recently written in Brazilian Portuguese about this
framework, per the São Paulo Perl Mongers "Equinócio" (Equinox) virtual
event. Although an English version of the article in in the plans, you
can figure a good deal out of the original one at
UPDATE: DataFlow is a fast-evolving project, and this article, as it was
published there, refers to versions 0.91.x of the framework. There has
been a big refactor since then and, although the concept remains the
same, since version 0.950000 the programming interface has been changed
violently.
Any doubts, feel free to get in touch.
SUPPORT
Perldoc
You can find documentation for this module with the perldoc command.
perldoc DataFlow
Websites
The following websites have more information about this module, and may
be of help to you. As always, in addition to those websites please use
your favorite search engine to discover more resources.
* Search CPAN
The default CPAN search engine, useful to view POD in HTML format.
* AnnoCPAN
The AnnoCPAN is a website that allows community annotations of Perl
module documentation.
* CPAN Ratings
The CPAN Ratings is a website that allows community ratings and
reviews of Perl modules.
* CPAN Forum
The CPAN Forum is a web forum for discussing Perl modules.
* CPANTS
The CPANTS is a website that analyzes the Kwalitee ( code metrics )
of a distribution.
* CPAN Testers
The CPAN Testers is a network of smokers who run automated tests on
uploaded CPAN distributions.
* CPAN Testers Matrix
The CPAN Testers Matrix is a website that provides a visual overview
of the test results for a distribution on various Perls/platforms.
Email
You can email the author of this module at "RUSSOZ at cpan.org" asking
for help with any problems you have.
Internet Relay Chat
You can get live help by using IRC ( Internet Relay Chat ). If you don't
know what IRC is, please read this excellent guide:
. Please be courteous
and patient when talking to us, as we might be busy or sleeping! You can
join those networks/channels and get help:
* irc.perl.org
You can connect to the server at 'irc.perl.org' and join this
channel: #sao-paulo.pm then talk to this person for help: russoz.
Bugs / Feature Requests
Please report any bugs or feature requests by email to "bug-dataflow at
rt.cpan.org", or through the web interface at
. You will be
automatically notified of any progress on the request by the system.
Source Code
The code is open to the world, and available for you to hack on. Please
feel free to browse it and play with it, or whatever. If you want to
contribute patches, please send me a diff or prod me to pull from your
repository :)
git clone https://github.com/russoz/DataFlow.git
AUTHOR
Alexei Znamensky
COPYRIGHT AND LICENSE
This software is copyright (c) 2011 by Alexei Znamensky.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
BUGS AND LIMITATIONS
You can make new bug reports, and view existing ones, through the web
interface at .
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